Study On The Modelling Of Two-dimensional Numerical Rubber Modified Asphalt Mixture And Simulation On The Virtual Loading Test

Taking crumb rubber modified asphalt mixture as the pavement material, not only,relieves the enormous environmental pressure caused by the waste tires, but improves thetemperature sensitivity problem attributed to the normal asphalt mixture. This will increasethe service lift of the asphalt pavement, which complies well with the contemporarytransportation development mode as the “Resource-conserving and Environment-friendly”.Therefore, the researchers at home and abroad pay close attention on the research on therubber modified asphalt mixture.As we all know, the performance of the rubber modified asphalt mixture is closelyrelated to the actual pavement performance. However, the traditional research on the rubbermodified asphalt mixture is peculiarly partial to the test of the macroscopic volume index,there exists some certain limitation in the method of the phenomenological research on therubber modified asphalt mixture. As a result, it result in the contradictory phenomenon,although the macro volume index is very close, its performance varies greatly for each other.The main cause of the phenomenon is ignoring the complexity of the micro structure in rubbermodified asphalt mixture, and, can’t reveal the physical mechanisms of deformation anddestruction of the materials, which can’t solve the pavement damage problem fundamentally.So, it’s very necessary to carry on research on the rubber modified asphalt mixture frommacroscopic research to micromechanics analysis. In addition, the research on the rubbermodified asphalt mixture based on the microstructure can reduce laboratory experiments withthe long cycle, huge workload and repetitive test, and it can save the huge investments in thedevelopment and popularization of the test equipment.In order to provide a new research technique on the rubber modified asphalt mixtureconcerning the design procedure and the failure mechanism, this paper takes the method ofnumerical simulation to analyze the failure mechanism of the rubber modified asphalt mixture,which adopts advanced mechanical analysis to break through the limitation of the experientialand experimental method based on the phenomenology. Based on this, the paper mainlycarried out the following research work:1. Combining X-ray CT non-destructive scanning techniques, digital image processingtechniques and numerical simulation method, the paper constructed the two-dimension finiteelement model of the rubber modified asphalt mixture based on the microstructure.2. Taking the rubber modified asphalt mixtures’ mechanical properties into account, the paper defined the rubber modified asphalt mortar (the mixture of the rubber modified asphaltand the fine aggregate whose particle size is smaller than2.36mm) as the viscoelasitc body,and analyze the viscoelastic characteristic. Meanwhile, the paper defined the coarseaggregates whose size is greater than2.36mm as elastomer. The paper adopts the Burgersmodel as the viscoelastic mechanics model of asphalt mortar, and, the linear elastic mechanicsmodel for the coarse aggregates.3. The paper adopted the method of finite element mechanics analysis with wideapplication at home and abroad to carry out the numerical simulation of the rubber modifiedasphalt mixture. And, it studied the stress and strain distribution of the asphalt mixture atdifferent test conditions(different rubber content, test temperature, graduation type) throughthe numerical simulation of the SCB test.4. Based on the SCB test, the paper accomplished the numerical simulation of thenotched SCB test, and evaluated the fracture characteristics of the rubber modified asphaltmixture with the J-integral. It focus on the effect on the J-integral of the crack tip withdifferent notch position, crack length and rubber content.5. The paper adopted the extended finite element method(XFEM) widely used in recentyears to simulate the crack propagation, and studied the stress variation rules at different stageof the crack propagation and the effect on the fracture characteristics due to different rubbercontent. In addition, combing the experiment and numerical simulation method of the notchedSCB test, the paper verified the validity and advantage of the numerical simulation method.